The mitral valve is a portion of the heart that is located between the chambers of the left atrium and the left ventricle. When the left ventricle contracts to pump blood throughout the body, the mitral valve closes to prevent the blood from being pumped back into the left atrium. In some patients, whether due to genetic malformation, disease or injury, the mitral valve fails to close properly causing a condition known as regurgitation, whereby blood is pumped into the atrium upon each contraction of the heart muscle. Regurgitation is a serious, often rapidly deteriorating, condition that reduces circulatory efficiency and must be corrected.
Two of the more common techniques for restoring the function of a damaged mitral valve are to surgically repair the valve, replace the valve with a mechanical valve, or to suture a flexible ring around the valve to support it. Each of these procedures is highly invasive because access to the heart is obtained through an opening in the patient's chest. Patients with mitral valve regurgitation are often relatively frail thereby increasing the risks associated with such an operation.
One less invasive approach for aiding the closure of the mitral valve involves the placement of a support structure in the cardiac sinus and vessel that passes adjacent the mitral valve. The support structure is designed to push the vessel and surrounding tissue against the valve to aid its closure. This technique has the advantage over other methods of mitral valve repair because it can be performed percutaneously without opening the chest wall. Examples of such devices are shown in U.S. patent application Ser. No. 10/003,910, “Focused Compression Mitral Valve Device and Method;” U.S. patent application Ser. No. 10/142,637, “Body Lumen Device Anchor, Device and Assembly;” U.S. patent application Ser. No. 10/331,143, “System and Method to Effect the Mitral Valve Annulus of a Heart;” and U.S. patent application Ser. No. 10/429,172, “Device and Method for Modifying the Shape of a Body Organ,” filed May 2, 2003. The disclosures of these patent applications are incorporated herein by reference.
The purpose of a support device in a lumen such as a vein or artery is to reshape a particular tissue area adjacent to the lumen. In order to be minimally invasive, the reshaping should be limited to the target tissue, such as the mitral valve annulus, and any reshaping of other tissue adjacent to the lumen should be minimized or avoided. For example, to treat mitral valve regurgitation, the device is placed in the coronary sinus to reshape the mitral valve annulus. Care should be taken to minimize the reshaping of other adjacent tissue, such as nearby arteries. See, e.g., the following applications (the disclosures of which are incorporated herein by reference): U.S. patent application Ser. No. 09/855,945, “Mitral Valve Therapy Device, System and Method” (published Nov. 14, 2002, as U.S. 2002/0169504 A1); U.S. patent application Ser. No. 09/855,946, “Mitral Valve Therapy Assembly and Method” (published Nov. 14, 2002, as U.S. 2002/0169502 A1). It is also advisable to monitor cardiac perfusion during and after such mitral valve regurgitation therapy. See, e.g., U.S. patent application Ser. No. 10/366,585, “Method of Implanting a Mitral Valve Therapy Device,” the disclosure of which is incorporated herein by reference.